The present invention relates to a capacitive tuning screw and particularly to a capacitive tuning screw that prevents the damage of crushing a circuit board or substrate when the tuning screw comes into contact with and exerts pressure on the circuit board or substrate.
Conventional capacitive tuning screws have self-locking threads to prevent undesired movement after adjustment is completed. Adjustment or calibration of the instrument involves adjusting the clearance between the tip of the screw and a corresponding capacitive element on the surface of a circuit board or substrate. Unfortunately, friction between the self-locking threads of the screw and the threads of the hole make it difficult to determine if the screw has contacted the circuit board. Conventional capacitive tuning screws therefore may be turned too far so that the circuit board or substrate is crushed and irreparably damaged.